The present invention relates to a container assembly for a motor vehicle, having a first container for a fuel and a second container for a liquid auxiliary agent. In this assembly, the second container is integrated into the first container.
SCR catalysts (Selective Catalytic Reduction) are known for reducing the content of nitrogen oxides in the exhaust gas from an internal combustion engine. In an SCR catalyst, the nitrogen oxides in the exhaust gas are reduced to elementary nitrogen and water in the presence of a reducing agent. Ammonia (NH3) is used as the reducing agent. To supply ammonia, use is generally made of an aqueous urea solution, which is injected into the exhaust line upstream of the SCR catalyst. To supply the aqueous urea solution, i.e. the reducing agent solution, a tank is provided, this being filled in a workshop in the course of a service, for example. In general, a tank volume of 15 to 30 liters is required. In principle, the volume of the tank for the reducing agent solution can also be reduced, especially if the driver himself can fill the tank outside of a service.
At low temperatures, the reducing agent solution freezes. The freezing point of the often-used solution AdBlue® is about −11° C., for example. One or more heating devices are therefore generally provided for the reducing agent tank in order to thaw the solution at low outside temperatures and to enable the metering system for the reducing agent solution to be made ready for metering.
There is already a known practice of combining the fuel tank of a motor vehicle with a tank for the liquid reducing agent. German Laid-Open Application DE 10 2009 000 094 A1, for example, describes a tank for holding an aqueous solution, wherein the tank is a standard tank which is integrated into a vehicle-specific component, in particular into the fuel tank of the vehicle. German Laid-Open Application DE 10 2009 009 676 A1 also describes the combination of a reducing agent tank with a fuel tank. Owing to the spatial proximity of the reducing agent tank and of the fuel container, freezing of the reducing agent in the reducing agent tank takes place only at a relatively late stage, even at low temperatures.